1. Field of the Invention
The present invention relates to a cap for covering a terminal of a high-tension cable for use in an automobile engine. The cap according to the present invention is intended to seal an opening formed in a rocker cover for receiving a spark plug electrically connected to a coil tower of a distributor or an opening for receiving a plug of a direct ignition coil in an adapter.
2. Description of the Prior Art
FIG. 1 depicts a conventional rubber cap 1 (rain cover) which is attached to a high-tension cable terminal in an automobile engine. The cap 1 covers a spark plug (not shown) mounted in a plug opening 4 formed in a rocker cover of the automobile engine for connection of the spark plug with a high-tension cable. The cap 1 comprises a hollow cap body 6, a U-shaped hood 10 extending outwardly from an intermediate portion of the cap body 6, and a cylindrical sealing flap portion 11 extending downwardly from the hood 10 and having an outwardly raised portion 11a. Because the sealing flap portion 11 is spaced from and extends along the outer peripheral surface of the cap body 6, a cylindrical recess 12 is formed therebetween, which enables the sealing flap portion 11 to elastically deform in a direction generally perpendicular to the direction in which the sealing flap portion 11 extends. When the cap 1 is appropriately mounted on the plug opening 4, the outwardly raised portion 11a of the sealing flap portion 11 engages the inner peripheral surface of the plug opening 4 to provide a seal against dirt, dust and water.
In the above-described construction, however, when the engine is started and the temperature of the rocker cover increases, the sealing flap portion 11 is subjected to heat deterioration, thereby lowering the sealing performance thereof. As a result, the trouble of water entering the plug opening 4 may arise. Furthermore, when the cap 1 is inattentively mounted on the plug opening 4, an upper edge of the plug opening 4 occasionally interferes with and turns up a lower edge of the sealing flap portion 11, as shown in FIG. 2. As a result, the sealing becomes incomplete.
If a heat-resistant material superior in quality is used for the cap 1, there are no technical problems associated with the sealing performance. However, because the almost maximum cost reduction is required in manufacturing automobile parts, any solutions overcoming the technical problems are not permitted at the expense of cost. Accordingly, there has been an increasing demand for the development of a practical means overcoming the conventional problems.